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(No Model.) 2 sheets sheet 1. T. N. VAIL 8: J. A. SEELY.

TELEPHONE'GENTRAL STATION APPARATUS.

Pate ted July 10; 1888.

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T. N. VAIL & JfA. SEELY. TELEPHONE CENTRAL STATION APPARATUS.

No. 385,977. I Patented July 10, 1888.

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UNITED STATES PATENT OFFIC ruuonoun N. VAIL, or BOSTON, MASSACHUSETTS, AND JOHN SEELY,

OF NEW YORK, N. Y.

TELEPHONE CENTRAL-STATION APPARATUS.

SPECIFICATION forming part of'Letters Patent No. 385,977, dated July 10, 1358.

Application filed March 1. 1888.

To all whom it .may concern;-

Beit known that we, THEODORE N. VAILand JOHN A. SEELY, citizens of the United States, and residents, respectively, of Boston,co unt v of Suffolk, State oflliiassachusetts, and of the city, county, and State of New York, have jointly invent-ed certain newand useful Improvements in Telephone Central-Station Apparatus, oi which the following is a specification.

Our invention is an improvementin certai ll details of construction of switch-boards for use in telephonecentralstations. Such switchhoards consist of a series of spring-jacks and the plugs designed for use in connection therewith. Spring-jacks consist .of two or more contact-points forming the terminals of a divided electrical circuit, such contacts being normally held together by the force ofsprings -upon which one or both of said contacts are fixed. A springjack for use in aground return circuit has but two sever'able contactpoints. A jack for use in a metallic returncircuit has four such contact-points. A plug formingthe terminal of a flexible connectingcord'is used with these jacks, and such plug has one or two contact-points, according as it is designed for use with a groundreturn or metallic circuit. These contact-points are so formed and arranged as to force' apart the spring-actuated points of the jack, and when the plug isin positionin thejack one-half the points of thejack are open and the points of the plug are substituted for such open points,

so that the circuit entering the jack is broken and connected to the plug and cord of. which it forms the terminal. Thesejacks are some times arranged with the plug-socket opening upon a horizontal plane, and when so arranged dust, dirt, and fragments of insulating material are liable to fall and lodge in the contactpoints, thus causing a break or opening in the circuit. 'Io prevent thi's,we have constructed Q i a springack having a dust-guard. This consists of a piece forming one contact-point placed between the opening or plug-socket and the severable points of the jack in such a position as to shed the dust and dirt, while it shields the contactpoints from the evil effects of such dust and dirt. It is preferably placed Serial No. 2fi5,783. -(No model.)

at angle with the plane of the-hole, opening, or pussage into the jaclr.

Another improvementconsists in the arrangements for placing the jacks in position eitherin'banks or singly, where they form parts of the electrical circuit, and may be readily removed for testing, cleaning, or repairing. The electrical conductors usually come to the tables or boards in the form of cables. These conductors are soldered to strips or pieces. of metal, a series of suchjst-ripsbeing firmly fixed in a portable block of insulating material. Each cable maybe attachedto one, two. or more 4 such portable blocks. Each block is shaped to rest in a framein such position as to bring the free ends of the strips referred to into registering position with-the free terminals of the anywhere near the spring-jacks, and may easily remove, replace. test, or repair'any' part. The jacks are placed in frames ofinsulating material in banks-of, sayfeightor tenyand'may be very expeditiously inserted and removed. The plugs for these jacks forming the terminals of flexible cords are usually held in, position with their bases resting upon fixed electrical contacts which register with electrical contacts on the base of the plug. If a plug forms the terminal of a'double conductor-cord, there are two insulated contacts on its base, and it we desire to have these two contacts rest upon two fixed contacts, respectively, and to take up this same position whenever the plug is removed from a jack and allowed to seek its normal position automatically under theinfiuence of aweightoperating' as a gravity take-up in a well-known manner, w'etn'ust provide special means for securing this result. For this purpose we have provided a cylindrical plug, one side of which is nattened, and a plug-socket having a similar outline to plug to correspond.

the cross-section of the plu In this arrangement a plug can only reach its normal position whenit is in the proper relative position with respect to the socketand contact-points. The accompanying drawings illustrate our invention.

Figure l is across'section of a switch-board on line 1 1, Fig. 2; and Fig. 2 is a plan view of a section of the switch-board. Fig. 3 shows the cabled conductors having terminals fixed in portable insulating-blocks.

In Fig. l are shown two springjacks consisting of sever-able points 0 0, held together by spring-pressure. F is a plug socket or passage from the surface of the board B, which is horizontally disposed. G is a dust-guard, also formingan electrical contact-point for one contact,p,ot' thejack-plug P. It islocated between the passage F and contactpoints c c. Dust,dir't, and fragments falling through F are shed off and caused to fall below the poiutsc 0, thus avoiding evil effects thereof. In these spring-jacks there are four sevei alile contacts 0 c and four free terminals like 112. There are also aseries of fixed terminals, t,.ininsulatingblock T in position to register and electrically connect with terminals m, and the meeting points of both mand t are soformed as tolock together and make good electrical contact. The conductors are soldered to the terminals 1; at the point a, Fig. 3. There is a space be tween board 13 and portable insulatingblocks T for the passage of the hand and to facilitate changes.

U is a bar or division, of which there are. ,several forming a frame for the portable insulating-blocks T. The conductors w of cable W are fanned out and soldered" to strips t t at n n. These terminals t are fixed in the portable insulating-blocks T in position to make contact with terminals in of the springjack.

The two conductors 'iand j, passing through flexible cords O, terminate in plugs P, having two electrical contacts, 1 and 2, at their base. There are also fixed contacts 3 and 4, with which it is desirable that contacts 1 and 2 should connect at all times when plug P is in its normal position, said plug being returned to its normal position by the gravity take-up w, as well understood. Now, in order that these plugs when released and automatically returned to their normal position by weight 10 may always assumethe same position, we provide a guide or passage having an eccenlric geometrical formation, and we form the We have chosen to make the guide circuiar, with a chord subtending a fewdegrees of the circle removed, as shown at s in Fig. 2. The cross-section of the plug is of similar outline and the entrance to the force of weight w and approaching socket F outof position, will right itself and sink into its normal position in proper position to unite contact-s 1 and 2 with 3 and t'res 'iectivelyaml uniformly.

What we'claim, and deslreto secure by Let-- ters Patent, is-

1. A spring-jack consisting of two or more severable contact-points, an .opening or passage to such points for the insertion of a jackplug, and a shield or dust-guard constructed of suitable material to shed or deflect falling dust or dirt, inovably supported between the mouth of the opening or passage and the severable contact-points.

2. In a springjack, the combination of two or more severablc contact-points, an opening or passage to such points forming a pl ugsocket, and a shield or dustguard forming an clcctri cal contact for the said plug, all arranged substantially as described.

3. A switch-board consisting of a frame or support, two series of blocks of insulating mat-erial fitting into said frame or support, located in two parallel planes, a series of electrical instruments composingtlre operativemechanism of a switch-board, such'as spring-jacks, having free terminals located in one series of blocks, one or more in each block, a series of electrical contacts having. free terminals lo cated in the second series of blocksin position to register with the terminals of the first so ries, and a series of electrical conductors con nected to the second series of contacts, one conductor for each contact.

4." The combination, in a switch-board, of two or more insulated electrical contacts located in a plug-socket having an eccentric geometrical outline or formation, a switch-plug of similar geometrical outline or formation,

"having one or more insulated electrical contacts in position to register with the first named contacts when said plug is inits normal position, and means for automatically rcturning such plug to its normal position when free to move, substantially as described.

5. A switch-board composed of a frame or support, one or more electrical instruments located in said frame having two or more free terminals, one or more portable blocks or sections of insulatingmaterial fitting into said frame, two or more conducting sections fixed in said blocks, their free terminals in position to register with the free terminals of the said electrical instru mcnts, and wires or conductors connected tosaid conducting sections, substantiall y as described.

.Signed at New York, county and State of New York, this 29th day of. February, 188-5.

' rruno. N. VAIL.

JOHN A. SEEL'Y.

Witnesses:

Wit. H. BAKER, J. MILTON Funny, Jr.

I (ii) 

